Need some quick help. All of a sudden, the carb on my 454 won't idle down. I don't have a tach but I'd say it stays at 1200/1300 RPM. One time it did idle down but then went back up. Help???? Going to Florida this Sudday really need to fix it.
Jim

Check for cable hanging up, return spring failure, sticking choke linkage, sticking fast idle linkage, loose or broken vacuum hoses, etc. Look closely at all the little rods and levers with a flashlight and see what is interfering with throttle return. The throttle lever on a warm engine should return to the hex headed stop screw.

Regardless of whether it's functional or not, don't overlook possible binding in the cruise-control cable/carb attach point.....

A little WD-40 (Oops, I meant to say PB-Blaster)where the cable exits the sheath will free things up there......

Like Billh says, if all the mechanical connectors & springs appear to be in-order, I'd suspect a vacuum** leak "somewhere".....

** Hmmmm....What's another English work using double "u"'s?

Jim have you been having this problem since the airconditioning work? I'm not sure but I think the 454 carb has an idle stop solenoid, maybe they messed with it while doing the work?
Ralph

Ralph, I think you nailed it. I took it to Truck Tech, the Newell factory authorized service center, and they looked and couldn't find anything. Of course at the time it was fine. Being an old steel guy, 40+ years in the business, I sold steel used in selenoid valves. It's stainless but still rusts. Anyway, they finally put in a new idle selenoid thing and it seems to be ok. I'll have it out tomorrow after some wheel balancing at the Goodyear store so I'll let you all know. Thanks for the advice.
Jim

After 3 days at the shop, they still can't figure out the high idle. There is a carb idle selenoid near the carb, and a plug with some wires that plugs into something that's next to the selenoid. When you unplug it, the idle goes down. Plug it back in and the idle goes up. Start up in the morning and the idle is fine, a/c on or off. Let it idle for an hour, it's still fine. Run it on the interstate for 15 minutes come back and the idle is high probably 1500rpm. They did all the linkage stuff, checked the vacuum hoses all that normal stuff and replaced what they called a "thermostat" somewhere in the front of the Barth accessible from the front and located left of the radiator/condenser, but it didn't do any good. the thermostat was about the size of a cigarette box, had some sort of a coil coming off it that wrapped around some kind of pipe in the a/c system to the left of the condenser. Sorry I seem so dumb, but I wasn't there. My wife was and she did a good job trying to get the thing straightened out, but you know how some mechanics are with women. Had to cancel our vacation. Any help?

By the way Ralph, they didn't put in a new idle selenoid as I previously thought. It was this thermostat thing.

Jim when its warmed up have you tried to open the dog house and move the carb linkage manualy to see if it will change your idle speed, one way it will speed up, the other it should return to the idle speed stop on the carb. If you can manualy slow it down to the normal idle then I would think that you have some problem with the cable or return springs, If after its warmed up I would then set the Idle speed .
I'm not a mech but with the help of all these Barth people I've manage to keep my 1976 running pretty good. Never had a break down on the road, once the electric choke wire came off and we were running pretty rich , with black smoke coming out the exhaust but we fixed that.

Good Luck Ralph

PS I have a question for all, does the 454 have an Idle stop solenoid? Now if you have one shouldnt you set the idle with the adjustment on this solenoid, then when you shut down it lets the throttle plate return to the stop to keep from dieseling. When Jim disconnected the wires on the sol the idle returned to normal. Just trying to figure it out. Ralph again

I guess I can answer my own question. I looked at my paperwork and I have an aftermarket carter carb with the idle stop sol. The orginial 454 didn't have the sol.
I would sure like to know what Jim disconnected to get the rpm down, sure sounds like an idle stop sol or some kind of unit to increase the rpm for maybe the ac unit. Just ramblin now so good luck Jim.

[This message has been edited by REGLOVER (edited September 17, 2005).]

[This message has been edited by REGLOVER (edited September 17, 2005).]

It's been years since I puttered with a 454, but it may be helpful to talk a minute about solenoids.

The Idle Stop solenoid is to keep the idle speed high until the engine warms up; it's a primitive emissions thingy. When the wires are disconnected, the idle goes down.

I'd first suspect a defective temp switch in that case.

The A/C solenoid is to increase the fuel supplky slightly (and hence RPM) at idle to compensate for the load imposed by the A/C compressor.

If the engine idles too fast under the conditions humbojb describes, if it were I, I'd also look to a sticky throttle plate shaft or a vacuum leak somewhere (although that's a long shot unless rough idle were noted). Not on this engine, but I did run across one where the throttle return spring was broken - some carbs have more than one, BTW.

This can also be caused by a sticking throttle cable, or even a cruddy linkage on the footfeed.

Anyway, I currently favor a defective temp swich in the idle solenoid circuit.

I opened the doghouse to see if I could manually slow down the idle but could not. Only when I disconnected the plug that I talked about did it slow down. Also, if I let it sit for an hour or so and start it up again, it will idle properly, until it gets out on the highway again and warms up.

The thing we are unplugging to make the idle come down is two inches in front of the idle stop. It looks like a solenoid with at least two vacuum hoses going into the opposite end of where it plugs into the wires. It is round, not square or rectangular. It looks like a metal fuel filter about 2 inches long by 1 1/2 in diameter. There are 4 wires that plug into it.Unplug the wires(one plug) it idles down.
Question, 1)Is the idle stop a solenoid itself. The idle stop appears to be one piece attached with two screws. About the size of a very small fist. 2) Where is the idle stop solenoid & what does it look like?
3) How could they "mess up" the idle stop solenoid?

FYI We revved the engine trying to get the idle to drop, sprayed with everything(Mechanic said wd40 dries out with the heat) Use qstate spray lubricant or zep lubricant they stick around longer. All to no avail. What would have changed with the ac repairs being done?
The throttle lever is retirning to the hex headed stop screw. They said they checked for vacuum leaks & found none yet. It works fine until it has been running for a while & always when we come back from a short test drive.

Tere Bianchi

[This message has been edited by humbojb (edited September 18, 2005).]

[This message has been edited by humbojb (edited September 18, 2005).]

Verbal descriptions rarely paint a perfect picture of objects. That's why a picture is worth a thousand words.

If you could post a digital photo, someone might be a able to i.d. the offending gizmo.

Look to see if you plugged the wrong wire into the AC idle bump solenoid.

Jim, Hows the idle problem going? I hope you have found and corrected the problem.

Ralph